1. Field of Industrial Application
The present invention relates to an apparatus and method of synthesizing an image through a texture mapping procedure.
2. Description of the Prior Art
There are known a variety of image synthesizing systems which can be used in game machines, image generating tools and the like. Such image synthesizing systems have a great technical subject with respect to how the quality of image can be improved to realize a so-called virtual reality. One of the known techniques for improving the quality of image is a technique called "texture mapping".
In the texture mapping, texture information is previously stored in a texture memory at its address locations. A given procedure is then carried out to determine texture coordinates of an object to be mapped at each pixel location. Based on these texture coordinates, the texture information is read from the texture memory to provide an image to be displayed. Thus, the texture mapping can represent an object with various textures, resulting in improvement of the image quality.
However, the prior art texture mapping can only represent differences in color and the like on the surface of the object. This raises a problem in that differences in material cannot be sufficiently represented.
There is a technique that represents the differences in material by setting information of brightness (illumination), translucence and the like for each object such as polygon (primitive surface) However, such a technique can only control the brightness and translucent information for each polygon. In order to set different brightness and translucent information at the first and second portions of a polygon, therefore, that polygon must be divided into separate polygon portions respectively corresponding to the first and second polygon portions. This increases the number of polygons to be processed.
There is also conceivable another technique that information of translucence or the like is stored in a texture memory at the respective address locations to represent the feeling of translucence in an object such as a polygon. However, when such a technique is to be used to provide different feelings of translucence between the first and second polygons, it is necessary to provide different texture information respectively for the first and second polygons. This increases the capacity of the texture memory and the processing load for writing and reading the texture information.